I don't have a wiring diagram handy, but the control box ignition switch produces "switched 12v" when the key is in the ON or Start positions. Switched 12v is on the purple or red/purple stripe wire where its used, whereas raw 12v is on the red wire.
Check the engine side of the 8 pin wiring harness connector (mates to the multiwire wiring harness cable that goes to the control box) for a purple wire. If none, then the switched voltage isn't used in the engine. If this is used to power the CDIs that generate the high voltage to fire your plugs, that's your problem. I don't think that is the case as once the engine is turning over, it self powers via the stator under the flywheel.
There is a black/yellow wire in that connector that goes to the CDIs that shuts down triggers when the key switch is in the OFF position, or the safety switch on the lanyard in the boat is open. With no control box this wire would be open circuited and of no influence........buttttt if you get the engine running, this is how you shut it down....you ground that wire to the engine block.
Get a helper. Pull a plug, all of them if you want to reduce the compression resistance to your effort and ground the body of the plug to the engine block with the HV lead attached. Pull the rope briskly and see if there is spark on the plug. If so, there is no need for worrying about switched 12v in the engine.
Couple more things: My 2002 90 liked its fuel to get started first thing of the day. A firm bulb and fuel enrichment are necessary...fuel enrichment is a little solenoid on the front-top of the engine with the yellow/brown stripe wire. I think you can manually pump it using the plastic button sticking out the top of it since you don't have the control box to energize it.
The second thing is that since the stator provides voltages to operate the CDIs and produce high voltage to the plugs. The crankshaft has to be spinning at about 200 or more RPM. Its a magnetically induced voltage and voltage is proportional to speed...too slow and voltage too low to fire plug.
The control box and associated cabling with the round 8 pin engine connector is for sale either on here or on ebay. The control box(es) that I know work(s) for that engine is the Mercury/Quicksilver Commander 2000 for external bulkhead mounting or 3000 for in bulkhead mounting. I prefer the 2000 as there is a separate lever for fast idle used when starting......very convenient. On the 3000 you have to push in the large black button and while holding in, move the shift/throttle forward to put it in the throttle only position. Once the engine starts and has warmed up adequately, you shift back to N position whereby the lever returns to its dual function capability.
